Gold nanoparticles, also called nanogold or colloidal gold, may be readily accumulated to be a gold clump in air, so as generally to be prepared in a solution. The gold nanoparticles smaller than 100 nm in size are usually allowed to turn the solution intense red, while the gold nanoparticles larger than 100 nm in size are then allowed to turn the solution blue or violet. Moreover, the gold nanoparticles are widely researched due to their specific optics features, electronic features, molecular recognition features and good biocompatibility thereof, and are at present applied to the fields of electron microscope, electronics, materials science, nano science and technology, biochemical sensing, optical detection, drug delivery, catalyzed reaction, disease treatment, electronic engineering, template induced crystallization and etc.
Further, the way for the production of gold nanoparticles is disclosed as U.S. Pat. No. 8,858,676, entitled “Nanoparticle production in liquid with multiple-pulse ultrafast laser ablation”, comprising a pulsed laser, a vibration mirror and a gold clump in a solution, the pulsed laser emitting a pulsed beam toward the vibration mirror, and the pulsed beam being reflected by the vibration mirror to the gold clump, so as to ablate the gold clump into nanoparticles having the average diameter of less than 100 nm.
However, it is less simple for laser ablation to control the shape and size of the gold nanoparticles, with the gold nanoparticles having larger particle diameters formed thereby. Therefore, how to reduce the particle diameters and uniforming the size of the gold nanoparticles is truly an important issue.